Command fuze

ABSTRACT

The shell includes RF detector circuitry, a pulse counter, and a firing circuit for a detonator which may be caused to explode during flight when it receives a predetermined number of radio pulses transmitted by ground command, or when, after receiving the predetermined number of pulses, the shell also receives a radio fire pulse by ground command. The fire pulse may be sent out by differential ranging system which continuously checks the distance to the shell and to the target and sends out the fire pulse when the distance is reduced to the predetermined one.

United States Patent Kern Sept. 5, 1972 COMMAND FUZE 72 I t t N 1 K So-ttsdal A Primary Examiner-Benjamin A. Borchelt 1 men or C c eAssistant Examiner-Thomas B. Webb [73] Assignee: Motorola, Inc.,Franklin Park, Ill. Attorney-Mueller & Aichele [22] Filed: Feb. 2, 1970I ABSTRACT [21] Appl. No.: 12,881

US. Cl ..102/70.2 P

The shell includes RF detector circuitry, a pulse counter, and a firingcircuit for a detonator which may [52] be caused to explode duringflight when it receives a 51 1111.01 ..F42c 13/04, F42c 11/00, F42015/40 Prsdflermined number of radio Pulses transmitted y 581 Field ofSearch ..102/70.2 P; 343/7 ground command, or when. after receiving thepredetermined number of pulses, the shell also [56] a Cited receives aradio fire pulse by ground command. The fire pulse may be sent out bydifferential ran ing 3 UNITED STATES PATENTS system which continuouslychecks the distance to the shell and to the target and sends out thefire pulse 32:23: et when the distance is reduced to the predetermined3,158,859 11/1964 Resnik ..343/7 3,014,215 12/1961 MacDonald ..102/70.2P 1 Claim, 6 Drawing Figures BATTERY I 22 r- R F counrsn Flame DETONATORDETECTOR CIRCUIT CIRCUIT I -----l --l CONSTANT DURATION PATENTEBNP' 5 ma3588.701

SHEET 2 0F 2 VARIABLY SPACED PULSE PRODUCER A szzzrazzzttt ONLY PULSESAND FIRING 1 RADAR 7 2e PULSE PRoDucER 1 FIG 4 so CONSTANT DURATIONVARIABLY SPACED DIFFERENTIAL PuLsEs AND FIRING A RANGE RADAR 1 2s PULSEPRODUCER A ARMING 8| FIRING PULSES TARGET RANGE ARMING PULSES FIRINGPULSE IIIIIIIIIIIIIIIIII BATTERY ENERGIZATION TIME \ARIATION IN BATTERYENERGIZATION TIME FLIGHT TIME INVENTOR. NEW C Kern BY M, 'fw

COMMAND FUZE BACKGROUND This invention relates to a fuze for a shellwhich will cause the shell to explode under radio control.

In many cases, more damage will be done to a target if a shell explodesat a predetermined distance on the approach side of the target. Forexample, a shell may pass right over a target and do it no damage;however, if the shell explodes over the target or just before it reachesthe target, the target may sustain severe damage. While proximity fuzesare known, a proximity fuze normally cannot distinguish between thebackground and the target. For example, if the target is behind a wall,the shell including a proximity fuze will be exploded by the proximityto the wall and not by the proximity to the target. Similarly, if thetrajectory of the shell to the target is low, the proximity fuze on theshell may cause the shell to explode due to proximity to the ground andnot due to proximity to the target. Time fuzes are known for shells, butwhen time fuzes are used the fuzes on each shell must be setindividually and the timing of the fuzes of the successive shells mustbe corrected in accordance with information noted by observing previousshells. Also round to round ballistic changes cause timingerrors.

It is an object of this invention to provide an improved radiocontrollable fuze for each shell.

It is an object of thisinvention to provide a fuze which will cause theshell of which it is a part to explode during its flight and after apredetermined time, or at a range which is determined after the shellhas been fired out of the gun.

SUMMARY In accordance with this invention, a pulse counter is mounted inthe shell and fuze means are provided in the shell to cause the fuze toexplode the bursting charge of the shell when the counter has counted apredetermined number of transmitted radio pulses. A radio pulsetransmitter is so located as to send pulses to be counted to the shell,the pulses produced by the pulse producer being all equal in length butbeing spaced in time by a variable amount. By varying the spacingbetween the pulses, the instant of the time of flight at which the shellexplodes may be determined. Since the spacing of the pulses produced bythe transmitter is variable while the guns are firing the shells, theeffect of the shell explosions may be observed and the pulse spacing maybe varied to cause the shell to explode at the most effective point inits flight. As another embodiment of this invention, the first series ofpulses may arm the fuze on the shell and then a second distinctivefiring pulse may be sent out either by the same transmitter or by asupplemental one. This firing pulse will cause all shells that are inflight and which have been armed to explode but will not cause shellscarrying unarmed fuzes to explode. The firing pulse may be transmittedunder control of a radio ranging device which measures the distance ofthe target from the ranging device or which measures the distancebetween the shell and the target.

DESCRIPTION The invention will be better understood upon reading thefollowing description in connection with the accompanying drawing inwhich:

FIGS. 1 and 2 indicate in block form two embodiments of this invention,and

FIGS. 3 to 6 are diagrams which are useful in explaining the operationof the device of this invention.

EXPLANATION Turning first to FIG. 1, a shell 10 is illustrated whichcarries, besides the usual detonator 12, a control or command means forcausing firing of the detonator 12. This means includes anantenna 14which may be built into the back end of the shell 10 and a radiofrequency detector 16, the output of which is coupled to a countingcircuit 18. The output of the counting circuit 18 is fed to a firingcircuit 20 whose output is in turn fed to the detonator 12. The elements16, 18 and 20 may be put on a chip such as the integrated circuit 22.The elements 12, 16, 18, and 20 are energized by a battery 24.

When the shell 10 of FIG. 1 is fired from a gun in the direction oftarget 26, as shown in FIG. 3, pulses from a constant duration variablyspaced pulse producer 28 are radiated by an antenna 30 which is theoutput of the pulse producer 28 to the antenna 14 on the shell 10. Theconcussion produced by the propelling charge for the shell 10 causes thebattery 24, which is in an inactive state until the occurrence of theconcussion, to become energized. As indicated by line 31 of FIG. 6, acertain length of time must pass before the battery 24 is energized.Also, as indicated by the lines 32 and 34 of FIG. 6, all batteries donot become energized after exactly the same time interval after theconcussion takes place. Therefore, the battery 24 becomes operativeduring a time after it has left the gun barrel indicated by the lines 32or 34 or some time thereinbetween. When the battery 24 is energized, thedescribed electronic elements 16 and 18 become operative to receive, todetect, and to count the pulses 36 (see FIG. 6) transmitted by thetransmitter 28 of FIG. 3. When a predetermined number of pulses 36, suchas 256 thereof, for example, have been counted by the counter 18, apulse is applied to the firing circuit 20 by the counter 18 to cause thedetonator 12 to explode. The observer can note when the shell 10 hasburst and by manipulation of the adjusting wheel 40 of the transmitter28, for example, the burst can be brought closer to the gun if it isbeyond the target 26 by making the time or spaces between the pulses 36smaller, or further from the gun by making the time or spaces betweenthe pulses 36 greater. Since the shell bursts occur only at the time thecounter counts 256 pulses (for example), the time of flight of the shell10 before it bursts is controllable by making the time between thepulses greater or less. A radio ranging system may be adapted to controlthe spaces between the pulses in accordance with the distance to thetarget.

It may be desirable to only arm the shell by means of spaced pulses ofuniform width and explode the shell by means of another firing pulsewhose time position is adjustable either manually or automatically. Sucha shell is shown in FIG. 2. In FIGS. 1 and 2, the same referencecharacters are applied to similar elements.

In FIG. 2, the chip 42 has applied thereto, besides the RF detector 16,the counter circuit 18, and the firing circuit 20, a pulse widthdiscriminator 44 and an AND circuit 46. The counter 18 and the widthdiscriminator 44 are connected between the output of the RF detector l6and respective input terminals of the AND circuit 46. The output of theAND circuit 46 is connected to the input of the firing circuit 20.

The operation of the shell of FIG. 2 is explained in conjunction withFIGS. 4 and 5 and line 48 of FIG. 6. Arming pulses 50, which are shortand uniform in duration but variably spaced in time, are counted by thecounter 18 of FIG. 2. When it has counted 256 pulses (for example), itapplies an output to the AND circuit 46, but at that time the ANDcircuit 46 has only one input thereto, whereby it has no output. At adesired time, a firing pulse 52 is transmitted to the shell 10. Thisfiring pulse 52 is wider than the arming pulses 36, whereby the firingpulse 52 gets through the pulse width discriminator circuit 44 whichapplies the second input pulse to the AND circuit 46. There now being apulse applied to each of the inputs of the AND circuit 46, the ANDcircuit 46 applies an output to the firing circuit 20 which causes thedetonator 12 to explode.

By use of a differential range radar apparatus 54, shown in FIG. 5, thefiring pulse 52 (FIG. 6) may be sent out automatically when the shelland the target 26 are at the right distance apart for inflicting maximumdamage on the target 26.

Since all the armed shells 10 that are in the air will be exploded bythe firing pulse 52, even though only the front one is at the desiredburst position, it may be desirable to adjust the spacing of the armingpulses 50 so that only the shells 10 that are near the target 26 arearmed. In this manner, several shells 10 which bracket the target 26 maybe exploded simultaneously, while the shells 10 that are still at toogreat a distance on the approach side of the target 26, will not beexploded.

The differential range radar 54 of FIG. 5 may be constructed inaccordance with the application of Neil C. Kern, Ser. No. 790,327, filedJan. 9, 1969, entitled Differential Ranging Systems, and assigned to M0-torola, Inc.

What is claimed is: l. A shell including: a detonator, an antenna, aradio detector connected to said antenna, a pulse counter connected tosaid radio detector and being responsive to an external command signal,a pulse width discriminator, an AND circuit having two input connectionsand an output connection, and the output of said counter being connectedto one input connection of said AND circuit, said pulse widthdiscriminator being connected between the output of said detector andthe other input of said AND circuit and the output of said AND circuitbeing connected to said detonator for causing said detonator to explodein response to said external command.

1. A shell including: a detonator, an antenna, a radio detectorconnected to said antenna, a pulse counter connected to said radiodetector and being responsive to an external command signal, a pulsewidth discriminator, an AND circuit having two input connections and anoutput connection, and the output of said counter being connected to oneinput connection of said AND circuit, said pulse width discriminatorbeing connected between the output of said detector and the other inputof said AND circuit and the output of said AND circuit being connectedto said detonator for causing said detonator to explode in response tosaid external command.